The present invention relates to containers and, more specifically, to paperboard containers for storage and shipment, being especially adapted for poultry and red meat products.
The prior art in this field lacks an effective means of incorporating a closable lid integral with the container while maintaining a simple blank design which could be assembled by simple container forming and container closing/sealing machines.
Attempts to use simple rectangular lid-integral blanks have failed because flanges hingedly attached to the lid sections need to be free-flapping in order to facilitate closure of the container. The free-flapping flanges create problems by inappropriately interfering with and being damaged by the wings, roller and stationary shapes past which the male forming mandrel and blank travel during assembly. In light of this defect, containers of this sort heretofore have only been formable by use of either complex one-piece container blanks or two-piece constructions. The lid-integral one-piece containers of the prior art generally have been formed from complicated blank designs. Characteristic of these blank designs has been wasteful generation of substantial amounts of paperboard scrap due to incorporation of irregularly shaped extensions, flaps, protuberances, gussets, tabs, slots, angles and the like. Exemplary of such are revealed in Olson Pat. No. 4,059,221; and Muise Pat. No. 4,572,424. Formation of the container from the blank generally has required costly complex pressing equipment requiring the employment of multiple operative steps.
The various geometric features of the complicated one-piece blanks have tended to be awkward and free-flapping. These features often have interfered with rollers or other machinery during assembly and thus could be easily damaged. Inherent design deficiencies have necessitated the use of high density paperboard to achieve the requisite strength.
Also typical of such prior constructions has been the tendency that the container spring open. This necessitates use of uneconomical quantities of adhesive to secure integrity of the container.
Two-piece containers of this general, prior art character often have required manual assembly. There has also been the difficulty inherent in achieving a consistently snug fit of the lid onto the box. Two-piece constructions have been generally awkward to handle during assembly and the subsequent filling operations; and have had relatively weak stacking strength in light of the amount of paperboard required per unit.
Each piece of such two-piece containers generally has been assembled by passage of a male forming mandrel pushing a paperboard blank past a series of wings, rollers and stationary shapes. Though this is an appropriately simple method of assembly, it has heretofore not been suitable for formation of containers from a one-piece, lid-integral paperboard blank, due to interference of the lid features with the wings and rollers.